
import compose from './compose';

/**
 * Creates a store enhancer that applies middleware to the dispatch method
 * of the Redux store. This is handy for a variety of tasks, such as expressing
 * asynchronous actions in a concise manner, or logging every action payload.
 *
 * See `redux-thunk` package as an example of the Redux middleware.
 *
 * Because middleware is potentially asynchronous, this should be the first
 * store enhancer in the composition chain.
 *
 * Note that each middleware will be given the `dispatch` and `getState` functions
 * as named arguments.
 *
 * @param middlewares The middleware chain to be applied.
 * @returns A store enhancer applying the middleware.
 *
 * @template Ext Dispatch signature added by a middleware.
 * @template S The type of the state supported by a middleware.
 */
export default function applyMiddleware(
  ...middlewares
) {
  return (createStore) =>(
      reducer,
      preloadedState
    ) => {
      const store = createStore(reducer, preloadedState)
      let dispatch = () => {
        throw new Error(
          'Dispatching while constructing your middleware is not allowed. ' +
            'Other middleware would not be applied to this dispatch.'
        )
      }

      const middlewareAPI = {
        getState: store.getState,
        dispatch: (action, ...args) => dispatch(action, ...args)
      }
      const chain = middlewares.map(middleware => middleware(middlewareAPI))
      dispatch = compose(...chain)(store.dispatch)

      return {
        ...store,
        dispatch
      }
    }
}